Estimation of legible font size for elderly people - Accessible design of characters in signs and displays and its standardization

Ken Sagawa*, Kenji Kurakata

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


Concept, methodology, and dissemination of outcomes for accessible design research are described in this paper, using vision research as an example. Characteristics of accessible design whose standpoint is different from that of assistive technology are explained in terms of methods for problem solving, objects of design, and public usefulness, and the role of standardization is emphasized from the point of public usefulness. As an example, the process of vision research for estimating minimum legible font size for elderly people is described. To develop a general estimation method for minimum legible font size, we collected fundamental data on visual acuity which changes with age and visual distance. Then, we compiled data on legibility of letters used in actual Japanese, derived a general estimating equation of legible font size, and confirmed the practical utility of the method. We have developed this method as a domestic and international standard. In addition, we have also applied this method to international comparative testing and have confirmed the validity of the results of this research. Finally, the entire process has been clarified by separating it into two procedural cycles: one for basic research, and the other for application, and the concept of "Full Research" has been addressed in the process.

Original languageEnglish
Pages (from-to)34-44
Number of pages11
Issue number1
Publication statusPublished - 2013 Jan 1
Externally publishedYes


  • Accessible design
  • Age-related change
  • Minimum legible font size
  • Standardization
  • Visual acuity

ASJC Scopus subject areas

  • Engineering(all)
  • Social Sciences(all)


Dive into the research topics of 'Estimation of legible font size for elderly people - Accessible design of characters in signs and displays and its standardization'. Together they form a unique fingerprint.

Cite this